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Finding the Fourth Proportional to 1,311.21, 1,808.90 and 786.94

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Solution

The fourth proportional to 1,311.21, 1,808.90 and 786.94 is: 1,085.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.21 : 1,808.90 = 786.94 : x
  2. Step 2: Convert to fraction form
    1,311.21/1,808.90 = 786.94/x
  3. Step 3: Cross multiply
    1,311.21x = 1,808.90 × 786.94
  4. Step 4: Simplify right side
    1,311.21x = 1,423,490.26
  5. Step 5: Solve for x
    x = 1,423,490.26/1,311.21
  6. Step 6: Final answer
    x = 1,085.63

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.